Spatial Taming and Trapping of Molecules

达德利·赫施巴赫得到了实验物理化学计划的支持，开发了一种操作和捕获具有非常低平动能的分子的设备。这将通过分子束膨胀冷却从高速对转转子外围流出的气体来实现，从而使转子尖端的运动抵消膨胀速度。也有一种选择是通过共同旋转转子来增加高于热能的速度。基本的可行性是用Xe建立的，这项技术正在开发中，并扩展到其他气体(O2、Cl2、HCl和CO)。正在进行的五项发展是：1)改进转子结构，消除设计弱点；2)增加超音速膨胀的压力，以实现更低的温度；3)提高真空度，以减少慢分子散射；4)开发收集慢分子的技术；5)使用脉冲气体喷嘴，以改善超音速波束的单向性。在这些发展的同时，还有a)低温化学的研究，特别是对OH的研究，b)使用不均匀的静电场和激光场来散射或聚焦慢粒子，以及c)通过分子衍射演示慢粒子的德布罗意性质。研究正在开发一种设备，其中分子可以冷却到非常低的温度，甚至比绝对零度低一度。在这种温度下，分子的速度为每秒几十米，与其大小相比，其波长更大。这完全改变了分子之间反应碰撞的性质，开辟了化学行为的新领域。这种装置可以使分子的速度不断增加，从而能够确定能量对过程的影响，并观察到向常规行为的转变。

Dudley Herschbach is supported by the Experimental Physical Chemistry Program to develop an apparatus for manipulating and trapping molecules with very low translational energies. This will be accomplished by molecular beam expansion cooling of gases exiting from the periphery of a high speed contra-rotating rotor such that the rotortip motion cancels out the expansion velocity. There is also the option of increasing the velocity above thermal by co-rotating the rotor. The basic viability was established using Xe and the technique is being developed and extends to other gases (O2, Cl2, HCl and CO). Five developments being made are to: 1) improve the rotor construction and eliminate design weaknesses; 2) increase the pressure for the supersonic expansion to achieve lower temperatures; 3) improve the vacuum to reduce slow molecule scattering; 4) develop techniques for collecting the slow molecules and 5) use a pulsed gas nozzle to improve the uni-directional nature of the supersonic beam. In parallel with these developments, there are a) studies of chemistry at low temperatures, specifically that of OH, b) use of inhomogeneous static and laser fields to scatter or focus the slow particles and c) demonstrations of the de Broglie nature of the slow particles by molecular diffraction.The studies are developing a device in which molecules can be cooled down to very low temperatures, as low as one degree above absolute zero of temperature. At these temperatures, the molecules have speeds of a few tens of meters per second and have wavelengths large compared with their size. This entirely changes the nature of the reactive collisions between molecules, opening up a new realm of chemical behavior. The device is such that the speed of the molecules can be increased continuously, enabling the effect of energy on the process to be determined and the change-over to conventional behavior to be observed.